Method of making self-supporting pleated filter

ABSTRACT

A self-supporting, pleated filter, and method of making the same. The method includes forming a plurality of pleats in a filter media that extend along a front face and a rear face. The pleats include a plurality of pleat tips and sloping side surfaces generally perpendicular to the direction of pleating. At least one planar reinforcing strip oriented in the direction of pleating is bonded to the pleat tips on the front face. At least one reinforcing member is positioned along the rear face of the filter media. The filter media is then cut to size. Frame members are applied for some applications. The reinforcing member may be a reinforcing strip oriented in the direction of pleating and bonded to the rear face of the filter media prior to the step of forming the plurality of pleats. A second planar reinforcing strip may optionally be bonded to the reinforcing strip pleat tips. The reinforcing member, the first reinforcing strip and the second reinforcing strip can be aligned to form a truss structure. Alternatively, reinforcing strips oriented perpendicular to the direction of pleating are bonded to the rear face of the filter media prior to the step of forming the pleats. In another embodiment, a reinforcing member is applied to the rear face of the filter media after the pleats have been formed. The reinforcing member is positioned along at least one of the sloping side surfaces of the pleats on the rear face in a direction perpendicular to the direction of pleating. In another embodiment, a scrim is positioned along the rear face of the filter media. The scrim can be bonded to the frame members, the filter media and/or a portion of the frame members extend over a perimeter of the scrim to secure it to the pleated filter.

TECHNICAL FIELD

[0001] The present invention is directed to a method of making aself-supporting, pleated filter with reinforcing structures that resistspleat deformation, and in particular, to a fully automated method ofmaking a pleated filter for air filtration.

BACKGROUND OF THE INVENTION

[0002] The surface area of filter media is a major factor in determiningflow resistance (i.e., pressure drop) and loading capacity of a pleatedfilter. The surface area of a pleated filter media is determined by thesize of the pleated filter, the depth of the pleats, and the pleatdensity. Since the external dimensions of pleated filters are oftenrestricted by the particular application, the number of pleats per inch(pleat density) can be increased to improve filtration performance.

[0003] The ability of air filter media to withstand operating pressuresis typically dependent upon the pleat count, the pleat depth and thestiffness of the filter media. The filter media can become unsteady whenair pressure is applied to one side. In the event the pleats deform orcollapse, a portion of the surface area can be reduced and the pressuredrop across the filter element will increase, further increasing theforce applied to the filter media.

[0004] U.S. Pat. No. 5,618,324 (Sommer, et al.) discloses aself-supporting, accordion folded filter element that includes a planarreinforcing strips bonded to the pleat tips by an adhesive.

[0005] A filter element available from Columbus Industries availableunder the product designation Microshield utilizes a glue bead toprovide longitudinal stabilization. The glue bead is applied before thefolding of the filter media and connects the folds with one another atthe point of application. However, the glue beads require a largequantity of melt bonding agent, resulting in increased cost.Additionally, the glue beads require the pleats to be closely spaced,limiting application of this technique to pleat counts generally greaterthan about six pleats per inch.

[0006] U.S. Pat. No. 4,547,950 (Thompson) discloses a method of spacingthe folds of a pleated filter media using a tapered assembly comb havinguniformly spaced teeth. Subsequently, a rigid divider is inserted intothe separated and folded media to produce a uniformly spaced filtermedia. Thompson does not disclose automated filter elementmanufacturing.

[0007] Therefore, there is a need for an automated method ofmanufacturing a pleated filter that has good flow characteristics andexhibits sufficient stability so that the pleats do not collapse ordeform when subjected to operating pressure.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to a self-supporting, pleatedfilter for air filtration, and method of making the same. The method ofthe present invention provides for assembly of the pleated filter by anautomated process at a high rate of manufacturing. The pleated filter ofthe present invention can be use with or without a reinforcing framestructure. The present method and apparatus may utilize conventionalfilter media, electret media, or a variety of other media suitable forair filtration, such for furnace applications.

[0009] In one embodiment, the method of making the self-supportingpleated filter includes forming a plurality of pleats in a filter mediathat extend along a front face and a rear face. The pleats include aplurality of pleat tips and sloping side surfaces generallyperpendicular to the direction of pleating. At least one reinforcingstrip oriented in the direction of pleating is bonded to the pleat tipson the front face to form a pleated filter. At least one reinforcingmember is positioned along the rear face of the filter media. The filtermedia is then cut to size. Frame members are optionally applied for somefiltration applications. Alternatively, the self-supporting pleatedfilter can be used without a frame or inserted into a permanent framethat permits the media to be easily changed.

[0010] In one embodiment, the step of positioning at least onereinforcing member includes locating one or more elongated reinforcingmembers oriented in the direction of pleating to the rear face of thefilter media prior to the step of forming the plurality of pleats. Aplurality of pleats are then formed in the reinforcing member during thestep of forming the pleats in the filter media. The pleats formed in thereinforcing member define reinforcing member pleat tips. A secondreinforcing strip may optionally be bonded to the reinforcing memberpleat tips. In one embodiment, the reinforcing member, the firstreinforcing strip and the second reinforcing strip are aligned to form atruss structure. The reinforcing member can optionally be bonded to thefilter media.

[0011] In another embodiment, the plurality of reinforcing membersoriented perpendicular to the direction of pleating are located on therear face of the filter media prior to the step of forming the pleats. Aplurality of pleats are formed in the reinforcing member during the stepof forming the pleats in the media. A second reinforcing strip orientedin the direction of pleating may be bonded to the pleat tips of the rearface over the reinforcing member.

[0012] In another embodiment, the reinforcing member is inserted intothe pleats on the rear face of the filter media after the pleats havebeen formed. At least one reinforcing member is positioned along atleast one of the sloping side surfaces of the pleats on the rear face ina direction perpendicular to the direction of pleating. A secondreinforcing strip oriented in the direction of pleating may optionallybe bonded to the pleat tips on the rear face over the reinforcingmember.

[0013] In another embodiment, a scrim is positioned along the rear faceof the filter media. The scrim can be bonded to the pleat tips along therear face. In one embodiment, a portion of the frame members extend overa perimeter of the scrim to secure it to the pleated filter. A scrimrefers to a porous mesh, netting or screen. The scrim can be constructedfrom various metals, plastics or paper-based products.

[0014] In another embodiment, a scrim can be substituted for thereinforcing strips located along the front face. The scrim is bonded tothe pleat tips on the front face to form a pleated filter. Any of thereinforcing members disclosed herein can be used along the rear face ofthe pleated filter.

[0015] The present method may also include the step of heat setting oneor more of the filter media and the reinforcing members after formingthe pleats. The step of applying the frame members typically includespositioning a portion of the frame members onto a portion of the frontface and the rear face of the filter media. An adhesive is typicallyapplied between the perimeter of the filter media and the frame members.The present method may be performed using a fully automated system. Thereinforcing members and reinforcing strips may be constructed fromvarious paperboard products, polymeric materials such as films, ormetals configured as elongated strips, scrims, strands or filaments.

[0016] The present invention is also directed to a self-supportingpleated filter. The filter media has a plurality of pleats defining aplurality of pleat tips and sloping side surfaces extending along afront face and a rear face. The pleat tips extend perpendicular to adirection of pleating. A planar reinforcing strip oriented in thedirection of pleating is bonded to the pleat tips along the front faceof the pleated filter. A reinforcing structure is provided along therear face of the pleated filter. A frame optionally extends around theperimeter of the filter media. In another embodiment, the pleated filtermay be inserted into, and subsequently removed from, a reusable frame.

[0017] In one embodiment, the reinforcing structure includes one or morereinforcing members extending in the direction of pleating generallyalong the contour of the pleat tips and sloping side surfaces of therear face. In one embodiment, the reinforcing members are bonded to thefilter media. A generally planar second reinforcing strip oriented inthe direction of pleating is bonded to reinforcing member pleat tips onthe pleated reinforcing member. In one embodiment, the reinforcingmember, the first reinforcing strip and the second reinforcing strip arepositioned to define a truss structure.

[0018] In another embodiment, the reinforcing structure includes atleast one reinforcing member oriented perpendicular to the direction ofpleating that is positioned generally along at least one of the slopingside surfaces of the rear face. In one embodiment, the frame extendsover distal ends of the reinforcing member. The reinforcing member mayalso be bonded to the filter media.

[0019] In another embodiment, the reinforcing structure includes a scrimthat extends over the rear face of the pleated filter. In oneembodiment, a portion of the frame extends over a perimeter of the scrimand onto the rear face of the filter media.

[0020] In another embodiment, a scrim is substituted for the reinforcingstrip located along the front face. The scrim is bonded to the pleattips on the front face to form a pleated filter. Any of the reinforcingmembers disclosed herein can be used along the rear face of the pleatedfilter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a schematic illustration of a system for performing themethod of the present invention.

[0022]FIG. 2 is a perspective view of a self-supporting pleated filterin accordance with the present invention.

[0023]FIG. 3 is a top schematic illustration of one embodiment of themethod of the present invention.

[0024]FIG. 4 is a top schematic illustration of an alternate method inaccordance with the present invention.

[0025]FIG. 5 is a sectional view of a self-supporting pleated filter inaccordance with the present invention.

[0026]FIG. 6 is a side sectional view of the pleated filter of FIG. 5.

[0027]FIG. 7 is a side sectional view of an alternate reinforcing memberin accordance with the present invention.

[0028]FIG. 8 is a side sectional view of an alternate reinforcing memberin accordance with the present invention.

[0029]FIG. 9 is a side sectional view of an alternate reinforcing memberin accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0030]FIG. 1 is a schematic illustration of a system 20 for performingthe method of the present invention. Filter media 22 is typicallyprovided on a continuous roll 24. The media 22 may be slit to thedesired width at slitting station 26. The media 22 may optionally bepreheated at a heating station 28 to facilitate processing. In theillustrated embodiment, the heating station 28 is an infrared heater.

[0031] In one embodiment, a reinforcing member 30 is applied to a rearface 32 of the media 22 at a location 34. As will be discussed in detailbelow, the reinforcing member 30 may be applied as one or morecontinuous strips oriented in the direction of pleating 36, as discretereinforcing members oriented perpendicular to the direction of pleating36, or a variety of other configurations. The reinforcing member 30 mayoptionally be bonded to the media 22 using a variety of techniques, suchas adhesive bonding, thermal bonding, solvent bonding, or ultrasonicbonding. In this embodiment, the location 34 is upstream of rotary-scorepleater 38 that scores the media 22 and the reinforcing member 30 priorto pleating. The rotary-score pleater 38 and pleat folding station 40may be modified to accommodate the increased thickness in the filtermedia 22 at the location of the reinforcing member 30.

[0032] The assembly of the media 22 and the reinforcing member 30 isadvanced through the rotary-score pleater 38 to a pleat folding station40. Infrared heaters 42 may optionally be provided for heat-setting thepleats 44. The pleats 44 are retained in an accumulator 46 until beingadvanced to a pleat spacing device 48 that retains the pleats 44 in thedesired pleat spacing. Pleat formation and pleat spacing may beperformed by a variety of methods, such as disclosed in U.S. Pat. No.4,798,575 (Siversson); U.S. Pat. No. 4,976,677 (Siversson); and U.S.Pat. No. 5,389,175 (Wenz).

[0033] The pleated filter media 60 is expanded to the desired pleatspacing in the pleat spacing device 48. One or more elongated, planarreinforcing strips 62 are applied to the pleat tips along the front face64 at the station 68 to maintain the pleat spacing. The reinforcingstrips 62 can be bonded to the pleat tips by various techniques, such asadhesive bonding, thermal bonding, solvent bonding, or ultrasonicbonding. The pleated filter media 60 and the reinforcing strip 62 definea pleated filter 72 that can be cut, machined handled or otherwiseprocessed. The reinforcing strips 62 provide dimensional stability tothe pleats 44 of the pleated filter 72. The pleated filter 72 can beused in filtration applications, with or without a frame structure, oras an insert into a permanent/reusable frame.

[0034] In another embodiment, a scrim 62 extending substantially acrossthe entire front face 64 is substituted for the planar reinforcingstrips 62. The scrim is bonded to the pleat tips to provide dimensionalstability to the pleated filter 72. Use of a scrim 62 extending acrossthe front face 64 may be used in combination with any of the reinforcingmembers discussed herein.

[0035] In the illustrated embodiment, one or more elongated, planarreinforcing strips 66 are optionally bonded to the rear face 32 of thepleated filter media 60 at the station 68. In one embodiment, thereinforcing strips 66 are located over the reinforcing member 30 andopposite the reinforcing strips 62 to form truss structures (see FIG.6).

[0036] In one embodiment, a continuous strip of frame material 80 isapplied to the ends of the pleated filter media 60 parallel to thedirection of pleating 36. An adhesive, such as a hot melt adhesive, isapplied to a first flange of a U-shaped channel formed from the framematerial 80 at the station 87. The adhesive for sealing the ends of thepleats 44 is applied at station 88. A hot melt adhesive is applied tothe second flange of the U-shaped channel at station 90. The framematerial 80 is bent into its U-shaped configuration at station 94. Theends U-shaped channel extend partially onto the front face 64 and rearface 32 of the pleated filter media 60 (see FIG. 5). An assemblyincluding the endless web of pleated filter media 60 and attached framematerial 80 is cut at station 86 to desired lengths. Alternatively, thepleated filter comprising the pleated filter media 60 and thereinforcing strips 62 can be cut to size before application of the framematerial 80.

[0037] The pleated filter media 60 and side frames members 92 arerotated 900 at location 91 to permit application of the end framemembers 96 at a station 98. Alternatively, the frame members 92, 96 canbe configured as two box structures that are positioned over the firstand second faces 32, 64, respectively, of the pleated filter 72, withoverlapped circumferential portions, such as disclosed in U.S. Pat. No.5,782,944 (Justice). In another embodiment, the frame member members 92,96 can be configured as a one-sided die-cut frame that is folded aroundthe pleated filter 72.

[0038] In embodiments where the pleated filter media 60 is used withoutframe members 92, 96, the pleated filter 72 exits the system 20 afterthe cutting station 86. Alternatively, a pleated filter 100 with a frame(see FIG. 2) exits the system 20. The pleated filters 72, 100 aretypically enclosed in suitable packaging.

[0039] Pleat spacing is typically about 3 to about 6 pleats per 25.4centimeters (1 inch). Pleat depth and the thickness of the filter 100 istypically about 25.4 centimeters to about 101.6 centimeters (1 inch to 4inches). For HVAC applications, the length and width of the filter 100is typically 30.5 centimeters×30.5 centimeters (12 inches×12 inches) toabout 50.8 centimeters×76.2 centimeters (20 inches×30 inches). Referenceto the front face 64 or rear face 32 is for purposes of description onlyand does not indicate an orientation of the pleated filter 100. Forexample, the reinforcing member 30 may be positioned upstream ordownstream in the air flow.

[0040] The resulting pleated filter 100 in accordance with the presentinvention is self-supporting. A pleated filter is self-supporting asdefined herein when the portion of the pleats 44 that are not directlysupported by the reinforcing member 30 or the reinforcing strips 62, 66do not collapse or bow excessively when subjected to the air pressuretypically encountered in forced air ventilation systems.

[0041] Stiffness of the filter media 22 is a factor in determining thesuitability of a particular filter media for use in the presentinvention. A Taber V-5 Stiffness Tester, Model 150-B, made by TeledyneTaber of North Tonawanda, N.Y., can be used to evaluate the stiffness ofthe filter media. The V-5 stiffness tester operates by bending aspecimen about 38.1 millimeters wide by about 38.1 millimeters long (1.5inches by 1.5 inches) to a prescribed angular of deflection andmeasuring the force, in stiffness units ranging from 0-10, used toobtain this deflection. In many heating, ventilating and airconditioning (HVAC) applications, the air pressure is generally about125 Pa to about 249.1 Pa (0.5 to 1.0 inch column of water) and the facevelocity is approximately 91.5 meters per minute (300 feet per minute).For HVAC filtration applications, the minimum stiffness value is greaterthan about 1.2 stiffness units, and preferably greater than about 1.5stiffness units and more preferably greater than about 2 stiffnessunits.

[0042] The U-shaped channel of the side frame members 92 serve tofurther stabilize the pleated filter media 60 and to seal the ends ofthe pleats 44 to prevent air bypass in the final pleated filter 100. Inone embodiment, a viscous adhesive such as a foamed adhesive, a filledadhesive or a caulk is used to seal the ends of the pleats 44 to theframe members 92, 96. Latex caulk is well suitable for this purposesince it is low cost and has low volatile organic content. On the otherhand, latex caulks have a long set time. Therefore, other adhesives,such as hot melt adhesives, are utilized to bond the two sides of theU-shaped channel formed from the frame material 80 to the pleat tips 44.A variety of techniques may be used for applying the frame members 92,96 to the pleated filter, such as disclosed in U.S. Pat. No. 4,731,047(Lobb).

[0043]FIG. 3 is a top schematic illustration of one embodiment of thepresent method for making a self-supporting pleated filter. Thereinforcing member 30 is oriented in the direction of pleating 36 alongthe rear face 32. In one embodiment, the reinforcing member 30 is bondedto the filter media 22. In the illustrated embodiment, the reinforcingmember 30 is strips about 6.4 centimeters to about 25.4 centimeters(0.25 inches to about 1 inch) wide. The filter media 22 and reinforcingmember 30 are subject to a pleating operation at station 40, resultingin pleats being formed in the reinforcing members 30. The pleatedreinforcing members 30 include reinforcing member pleat tips 120.

[0044] The reinforcing strip 62 is applied to the front face 64 of thepleated filter media 60 at the station 68 to form the pleated filter 72(see FIG. 1). The reinforcing strip 66 is also bonded to the reinforcingmember pleat tips 120 at the station 68. The reinforcing strips 62, 66provide added dimensional stability to the pleated filter media 60 tofacilitate machine handling. Frame material 80 is optionally applied tothe edges of the pleated filter media 60 parallel to the direction ofpleating 36 to form side frame members 92, as previously discussed. Thecombination of the pleated reinforcing member 30, the reinforcing strips66 along the rear face 32 and the reinforcing strip 62 along the frontface form a truss structure that gives the pleated filter media 60 itsself-supporting properties (see FIG. 6). The pleated filter media 60 andframe material 80 are cut to length at the cutting station 86.Alternatively, the pleated filter 72 can be cut to size prior toapplication of the frame material 80.

[0045]FIG. 4 is a top schematic illustration of an alternate method inaccordance with the present invention. The reinforcing member 30 isapplied to the media 22 at discrete locations along the rear surface 32perpendicular to the direction of pleating 36. The reinforcing member 30may optionally be bonded to the filter media 22. The assembly of thefilter media 22 and the reinforcing member 30 is subject to the pleatingoperation at the station 40 so that the reinforcing member 30 issimultaneously pleated with the filter media 22.

[0046] The reinforcing strip 62 is applied to the front face 64 of thepleated filter media 60 at the station 68 to form the pleated filter 72(see FIG. 1). Reinforcing strips 66 are optionally applied to the pleattips along the rear face 32 at the station 68. In the embodimentillustrated in FIG. 4, the side frame members 92 preferably extend ontothe rear face 32 of the pleated filter media 60 so that stresses imposedon the reinforcing members 30 are transmitted to the frame members 92.

[0047] Turning back to FIG. 1, the reinforcing member 30 may optionallybe inserted directly into the pleated filter media 60 at a station 70.The reinforcing member 30 can be preformed to correspond to the pleattips and sloping side surfaces of the pleats 44 (see FIG. 7). Thereinforcing member 30 may optionally be bonded to the pleated filtermedia 60. In one embodiment, the station 70 is located upstream of thestation 68 where the reinforcing strip 66 is applied to the rear face32. In this embodiment, the reinforcing strip 66 helps to retain thereinforcing member 31 to the pleated filter media 60. Alternatively, thereinforcing member 30 may be inserted into the pleats of the pleatedfilter media 60 at station 70′ located downstream of the station 68.

[0048] The reinforcing member 30 may be a scrim extending across therear face 32 prior to forming the frame members 92, 96. The stations 70or 70′ may be used to position a scrim along the rear face 32. The scrimmay optionally be adhesively bonded to the pleated filter media 60. Inthis embodiment, the reinforcing strip 62 will be applied to the frontface 64 to maintain pleat spacing and facilitate machine handling, butthe reinforcing strip 66 along the rear face 32 may be unnecessary.

[0049] The filter media 22 may be paper, porous films of thermoplasticor thermoset materials, nonwoven webs of synthetic or natural fibers,scrims, woven or knitted materials, foams, or electret orelectrostatically charged materials. The filter media 22 may alsoinclude sorbents, catalysts, and/or activated carbon (granules, fibers,fabric, and molded shapes). Electret filter webs can be formed of thesplit fibrillated charged fibers as described in U.S. Pat. No. RE30,782. These charged fibers can be formed into a nonwoven web byconventional means and optionally joined to a supporting scrim such asdisclosed in U.S. Pat. No. 5,230,800 forming an outer support layer.Alternatively, the filter media 22 can be a melt blown microfibernonwoven web, such as disclosed in U.S. Pat. No. 4,817,942 which can bejoined to a support layer during web formation as disclosed in thatpatent, or subsequently joined to a support web in any conventionalmanner. The reinforcing member 30 and the reinforcing strips 62, 66 maybe constructed from various paper products, polymeric materials, ormetals. These materials can be configured as strips, films, scrims,strands or filaments. The frame members are typically paper products,such as chipboard, or polymeric materials.

[0050]FIGS. 5 and 6 illustrate a self-supporting pleated filter 200 thatcorresponds with the method illustrated in FIG. 3. The pleated filtermedia 60 is retained within a pair of opposing side frame members 92 andend frame members 96. The reinforcing member 30 of FIG. 3 correspondsgenerally to the reinforcing member 202 that extends in the direction ofpleating 36 and generally follows the contour of the pleat tips 204 andsloping side surfaces 206, 208. That is, the reinforcing member 202extends into the pleats along the z-axis. The z-axis is the axisperpendicular to a plane defined by the front face 64 or the rear face32 of the pleated filter media 60. The reinforcing member 202 has aplurality of reinforcing member pleat tips 210. Reinforcing strip 66 isoptionally bonded to the reinforcing member pleat tips 210 along therear face 211. Reinforcing strip 62 is oriented in the direction ofpleating 36 and bonded to the pleat tips 204 along the front face 212and opposite the reinforcing member 202 to form a truss structure.

[0051]FIG. 7 is a perspective view of an alternate self-supportingpleated filter 230 that corresponds generally to the method illustratedin FIG. 4. The reinforcing member 30 corresponds generally to thereinforcing member 232. The reinforcing member 232 extends into thepleats along the z-axis, perpendicular to the rear face 32. Thereinforcing member 232 can be bonded to the pleated filter media 60,retained by the side frame members 92, or a combination thereof. Thereinforcing strip 66 may optionally be provided along the rear face 32.In the illustrated embodiment, the reinforcing member 232 has a V-shapethat extends along a pair of opposing side surfaces 234, 236 of twopleats 238. In an alternate embodiment, the reinforcing structure 232extends across a single pleat. In one embodiment, the reinforcing member232 is a metal scrim.

[0052]FIG. 8 illustrates an alternate reinforcing structure 250 that isdeposited in the pleats 252, rather than being pleated with the filtermedia 60. The reinforcing structure 250 is typically inserted into thepleats 252 of the pleated filter media 60 prior to application of theoptional reinforcing strip 66. In the embodiment illustrated in FIG. 8,the reinforcing structure 250 extends along a single pleat 252 andincludes side extensions 254 that extend parallel to the rear face 32over additional pleats. In order to minimize pressure drop across thepleated filter media 60, the reinforcing structure 250 is a porousmaterial, such as a scrim. The reinforcing structure 250 may be retainedto the pleated filter media 60 by bonding, by the optional reinforcingstrip 66 and/or by the side frame members 92. In an alternateembodiment, the reinforcing structure 250 has a triangular shapecorresponding to the shape of the pleats 252.

[0053]FIG. 9 illustrates an alternate pleated filter 270 with acontinuous reinforcing structure 272 extending across the rear surface32 of the filter media 60. Reinforcing strips 62 are located along thefront face 64 (see FIG. 1). Reinforcing strip 66 is optionally providedon the rear face 32 over or under the reinforcing structure 272. Thereinforcing structure 272 may be retained to the pleated filter media 60by bonding to the frame members 92, 96 and/or the filter media 60, bythe optional reinforcing strip 66 and/or by the side frame members 92.The continuous reinforcing structure 272 may be a scrim, mesh, screen orother porous material. In an alternate embodiment, the continuousreinforcing structure 272 is bonded to the pleat tips along the frontface 64 in place of the reinforcing strips 62.

[0054] The complete disclosures of all patents, patent applications, andpublications are incorporated herein by reference as if individuallyincorporated. Various modifications and alterations of this inventionwill become apparent to those skilled in the art without departing fromthe scope and spirit of this invention, and it should be understood thatthis invention is not to be unduly limited to the illustrativeembodiments set forth herein.

What is claimed is:
 1. A method of making a self-supporting, pleated airfilter using a fully automated process, comprising the steps of: forminga plurality of pleats in a filter media extending along a front face anda rear face, the pleats comprising a plurality of pleat tips and slopingside surfaces generally perpendicular to a direction of pleating;bonding at least one planar, first reinforcing strip oriented in adirection of pleating to the pleat tips on the front face of a filtermedia to form a pleated filter capable of machine handling; positioningat least one reinforcing member in the pleats along the rear face of thepleated filter; and cutting the pleated filter to size.
 2. The method ofclaim 1 further comprising the step of applying frame members to thepleated filter.
 3. The method of claim 1 wherein the step of positioningat least one reinforcing member comprises the steps of: positioning thereinforcing member oriented in the direction of pleating to the rearface of a filter media prior to the step of forming a plurality ofpleats; and forming a plurality of pleats in the reinforcing memberduring the step of forming the pleats in the filter media.
 4. The methodof claim 3 comprising the step of bonding a planar second reinforcingstrip oriented in the direction of pleating to the pleat tips.
 5. Themethod of claim 3 wherein the pleats formed in the reinforcing memberdefine reinforcing member pleat tips, the method comprising the step ofbonding a planar second reinforcing strip oriented in the direction ofpleating to the reinforcing member pleat tips to form a truss structure.6. The method of claim 4 wherein each of the reinforcing member, thefirst reinforcing strip and the second reinforcing strip comprise awidth of about 6.4 millimeters to about 25.4 millimeters.
 7. The methodof claim 1 wherein the step of positioning at least one reinforcingmember comprises the steps of: positioning a plurality of reinforcingmembers oriented perpendicular to the direction of pleating to the rearface of a filter media prior to the step of forming the pleats; andforming a plurality of pleats in the reinforcing members during the stepof forming the pleats in the filter media.
 8. The method of claim 7wherein the reinforcing member extends across at least one sloping sidesurface of a pleat.
 9. The method of claim 7 wherein the reinforcingmember extends across at least one pleat.
 10. The method of claim 7comprising the step of bonding a second reinforcing strip oriented inthe direction of pleating to the pleat tips on the rear face.
 11. Themethod of claim 1 wherein the step of positioning the reinforcing membercomprises the steps inserting the reinforcing member along at least oneof the sloping side surfaces of the pleats on the rear face in adirection perpendicular to the direction of pleating after the step offorming the plurality of pleats in the filter media.
 12. The method ofclaim 11 comprising the step of bonding a planar second reinforcingstrip oriented in the direction of pleating to the pleat tips on therear face over the reinforcing member.
 13. The method of claim 1 whereinthe step of positioning the reinforcing member comprises positioning aplanar scrim that extends across the rear face of the filter media. 14.The method of claim 1 wherein the reinforcing member and reinforcingstrips comprises one of films, scrims, strands or filaments constructedfrom paper products, metals, polymeric materials, or combinationsthereof.
 15. The method of claim 1 comprising the step of bonding thereinforcing member to the filter media.
 16. The method of claim 1wherein the step of applying the frame members comprises extending aportion of the frame members over distal ends of the reinforcing member.17. The method of claim 1 wherein the step of applying frame memberscomprises the steps of: applying side frame members to the pleatedfilter parallel to the direction of pleating; and applying end framemembers to the pleated filter perpendicular to the direction ofpleating.
 18. The method of claim 1 wherein the step of pleating thefilter media comprises the step of forming about 3 to about 6 pleats per2.54 centimeters (1 inch).
 19. The method of claim 1 wherein the step ofpleating the filter media comprises the step of forming a pleat depth ofabout 25.4 centimeters to about 101.6 centimeters (1 inch to 4 inches).20. The method of claim 1 comprising the step of forming a pleated airfilter wherein the front face has a length and a width of about 30.5centimeters by about 30.5 centimeters (12 inches×12 inches) to about50.8 centimeters by about 76.2 centimeters (20 inches×30 inches). 21.The method of claim 1 comprising the step of selecting a filter mediawith a stiffness of at least 1.2 stiffness units.
 22. The method ofclaim 1 comprising the step of selecting a filter media with a stiffnessof at least 1.5 stiffness units.
 23. A method of making aself-supporting, pleated filter, comprising the steps of: bonding atleast one reinforcing member oriented in a direction of pleating to arear face of a filter media; forming a plurality of pleats in a filtermedia and the reinforcing member along a front face and the rear face,the pleats comprising a plurality of pleat tips and sloping sidesurfaces generally perpendicular to a direction of pleating, thereinforcing member defining a plurality of reinforcing member pleat tipscorresponding generally to the pleat tips; bonding a planar firstreinforcing strip oriented in the direction of pleating to the pleattips on the front face to form a pleated filter; bonding a planar secondreinforcing strip to the reinforcing member pleat tips on the rear faceopposite the reinforcing member; and cutting the pleated filter to size.24. The method of claim 23 further comprising the step of applying framemembers to the pleated filter.
 25. A method of making a self-supporting,pleated filter, comprising the steps of: forming a plurality of pleatsin a filter media along a front face and the rear face, the pleatscomprising a plurality of pleat tips and sloping side surfaces generallyperpendicular to a direction of pleating; bonding a planar firstreinforcing strip oriented in the direction of pleating to the pleattips on the front face to form a pleated filter; positioning at leastone reinforcing members generally along at least one of the sloping sidesurfaces of the rear face and perpendicular to the direction ofpleating; bonding a planar second reinforcing strip oriented in thedirection of pleating to the pleat tips on the rear face; and cuttingthe pleated filter to size.
 26. The method of claim 25 furthercomprising the step of applying frame members to the pleated filter. 27.A method of making a self-supporting, pleated air filter using a fullyautomated process, comprising the steps of: forming a plurality ofpleats in a filter media extending along a front face and a rear face,the pleats comprising a plurality of pleat tips and sloping sidesurfaces generally perpendicular to a direction of pleating; bonding aplanar reinforcing scrim to the pleat tips on the front face of a filtermedia to form a pleated filter capable of machine handling; positioningat least one reinforcing member in the pleats along the rear face of thepleated filter; and cutting the pleated filter to size.
 28. Aself-supporting, pleated filter, comprising: a filter media having aplurality of pleats defining a plurality of pleat tips and sloping sidesurfaces extending along a front face and a rear face, the pleat tipsbeing perpendicular to a direction of pleating; a reinforcing structurecomprising; a generally planar first reinforcing strip oriented in thedirection of pleating bonded to the pleat tip along the front face; areinforcing member extending in the direction of pleating generallyalong the contour of the pleat tips and sloping side surfaces on therear face, the reinforcing member having reinforcing member pleat tips;and a generally planar second reinforcing strip bonded to thereinforcing member pleat tips.
 29. The article of claim 28 wherein thereinforcing member and reinforcing strips comprises one of films,scrims, strands or filaments constructed from paper products, metals,polymeric materials, or combinations thereof.
 30. The article of claim28 wherein the reinforcing member is bonded to the filter media.
 31. Thearticle of claim 28 wherein the frame extends onto a portion of thefront face and the rear face.
 32. The article of claim 28 wherein theperimeter of the filter media is adhesively bonded to the frame.
 33. Thearticle of claim 28 wherein the reinforcing member, first reinforcingstrip and second reinforcing strip comprise a truss structure.
 34. Thearticle of claim 28 wherein the filter media comprises about 3 to about6 pleats per 2.54 centimeters (1 inch).
 35. The article of claim 28wherein the pleats have a depth of about 25.4 centimeters to about 101.6centimeters (1 inch to 4 inches).
 36. The article of claim 28 whereinthe filter media has a stiffness of at least 1.2 stiffness units. 37.The article of claim 28 wherein the filter media has a stiffness of atleast 1.5 stiffness units.
 38. The article of claim 28 comprising aframe extending around a perimeter of the filter media.
 39. Aself-supporting, pleated filter, comprising: a filter media having aplurality of pleats defining a plurality of pleat tips and sloping sidesurfaces extending along a front face and a rear face, the pleat tipsbeing perpendicular to a direction of pleating; a reinforcing structurecomprising; a generally planar first reinforcing strip oriented in thedirection of pleating and bonded to the pleat tips along the front face;and at least one reinforcing member oriented perpendicular to thedirection of pleating and extending generally along at least one of thesloping side surfaces of the rear face.
 40. The article of claim 39wherein the reinforcing member and reinforcing strips comprises one offilms, scrims, strands or filaments constructed from paper products,metals, polymeric materials, or combinations thereof.
 41. The article ofclaim 39 wherein the frame extends over distal ends of the reinforcingmember.
 42. The article of claim 39 wherein the reinforcing member isbonded to the filter media.
 43. The article of claim 39 comprising aframe extending around a perimeter of the filter media.
 44. Aself-supporting, pleated filter, comprising: a filter media having aplurality of pleats defining a plurality of pleat tips and sloping sidesurfaces extending along a front face and a rear face, the pleat tipsbeing perpendicular to a direction of pleating; a reinforcing structurecomprising; a generally planar scrim bonded to the pleat tips across thefront face; and at least one reinforcing member oriented perpendicularto the direction of pleating and extending generally along at least oneof the sloping side surfaces of the rear face.